Researchers at Mount Sinai School of Medicine have found that even small amounts of damage to heart muscle during coronary artery bypass grafting (CABG) is associated with an increased risk of death, even among patients who initially do well following surgery. The study is published in the February 9 issue of the Journal of the American Medical Association (JAMA).

Small elevations of troponin and creatine phosphokkinase – chemicals called enzymes that are released by heart muscle cells when they are damaged – have often been dismissed as unimportant. But Mount Sinai researchers examined data from almost 19,000 bypass patients and found a direct correlation between enzyme levels and mortality.

"There is a strong, graded association of enzyme elevation with risk of death; the greater the elevation, the greater the risk," said the study's lead author Michael J. Domanski, MD, Professor, Cardiology, Mount Sinai School of Medicine, and Director of Heart Failure Research at Mount Sinai Heart. "The increased risk is present even at low enzyme levels and continues for some years.

"The findings are particularly useful in designing clinical trials of new heart treatments, and may ultimately prove useful in evaluating the quality of procedures performed on the heart," said Dr. Domanski.